/*
 * Copyright (C) 2010 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.primitives;

import com.google.caliper.BeforeExperiment;
import com.google.caliper.Benchmark;
import com.google.caliper.Param;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Random;

/**
 * Microbenchmark for {@link UnsignedBytes}.
 *
 * @author Hiroshi Yamauchi
 */
public class UnsignedBytesBenchmark {

    private byte[] ba1;
    private byte[] ba2;
    private byte[] ba3;
    private byte[] ba4;
    private Comparator<byte[]> javaImpl;
    private Comparator<byte[]> unsafeImpl;

    // 4, 8, 64, 1K, 1M, 1M (unaligned), 64M, 64M (unaligned)
    // @Param({"4", "8", "64", "1024", "1048576", "1048577", "6710884", "6710883"})
    @Param({"4", "8", "64", "1024"})
    private int length;

    @BeforeExperiment
    void setUp() throws Exception {
        Random r = new Random();
        ba1 = new byte[length];
        r.nextBytes(ba1);
        ba2 = Arrays.copyOf(ba1, ba1.length);
        // Differ at the last element
        ba3 = Arrays.copyOf(ba1, ba1.length);
        ba4 = Arrays.copyOf(ba1, ba1.length);
        ba3[ba1.length - 1] = (byte) 43;
        ba4[ba1.length - 1] = (byte) 42;

        javaImpl = UnsignedBytes.lexicographicalComparatorJavaImpl();
        unsafeImpl = UnsignedBytes.LexicographicalComparatorHolder.UnsafeComparator.INSTANCE;
    }

    @Benchmark
    void longEqualJava(int reps) {
        for (int i = 0; i < reps; ++i) {
            if (javaImpl.compare(ba1, ba2) != 0) {
                throw new Error(); // deoptimization
            }
        }
    }

    @Benchmark
    void longEqualUnsafe(int reps) {
        for (int i = 0; i < reps; ++i) {
            if (unsafeImpl.compare(ba1, ba2) != 0) {
                throw new Error(); // deoptimization
            }
        }
    }

    @Benchmark
    void diffLastJava(int reps) {
        for (int i = 0; i < reps; ++i) {
            if (javaImpl.compare(ba3, ba4) == 0) {
                throw new Error(); // deoptimization
            }
        }
    }

    @Benchmark
    void diffLastUnsafe(int reps) {
        for (int i = 0; i < reps; ++i) {
            if (unsafeImpl.compare(ba3, ba4) == 0) {
                throw new Error(); // deoptimization
            }
        }
    }

    /*
     * try { UnsignedBytesBenchmark bench = new UnsignedBytesBenchmark(); bench.length = 1024;
     * bench.setUp(); bench.timeUnsafe(100000); } catch (Exception e) { }
     */
}
